The Internet is used for a variety of reasons, including electronic commerce, exchanging information such as electronic mail, retrieving information doing research, and the like. Many standards have been established for exchanging information over the Internet, including the World Wide Web (WWW). The WWW allows a server computer system (i.e., web server or Web site) to send documents (e.g., Web pages) to a remote client computer system. The remote client computer system can then display the Web pages. Each resource (e.g., computer or Web page) of the WWW is uniquely identifiable by a Uniform Resource Locator (URL). To view a specific Web page, a client computer system specifies the URL for that web page in a request (e.g., a HyperText Transfer Protocol (HTTP) request). The request is forwarded to the Web server that can provide the requested Web page. When that Web server receives the request, it sends the requested Web page to the client computer system. When the client computer system receives that Web page, it typically displays the Web page using a browser. A browser is typically an application program for requesting and displaying Web pages.
A network address is a location to which network messages (“messages”) are sent or from which messages are received. HTTP requests and responses are normally directed to specific network addresses using a transport control protocol/Internet protocol (TCP/IP). These messages can identify a computing device as an intended recipient of the message by specifying an IP address. IP addresses are conventionally specified using a sequence of numbers. For example, in version 4 of IP (IPv4), network addresses are specified using 32 bits. An IPv4 address can be 192.168.128.64, which has four 8-bit bytes. Other protocols may use different network addressing schemes.
Network addresses are sometimes specified in ranges (“segments” or “subnets”). For example, an IPv4 range can be specified as 192.168.128.0/24. In this notation, the value after the slash indicates the number of bits that are used to specify the range. Because 8 bits are not specified (32 bits total for the network address less 24 bits for the range), the actual range is 192.168.128.0 to 192.168.128.255. If the range is specified as 192.168.0.0/16, the actual range is 192.168.0.0 to 192.168.255.255.
To ensure uniqueness of IP addresses across the Internet, a central authority distributes IP addresses. Only one device on the Internet can have a particular IP address. If this were not so, a network message may be routed incorrectly to a network device that is not the intended recipient of the message. IP addresses are generally allocated in ranges. As examples, a city or township may be provided a range of network addresses, or a large company may be provided a range of network addresses. For example, a city may be provided the range 192.168.0.0/16. These entities may then subdivide these ranges. For example, the city may allocate 192.168.1.0/24 to a company located in that city and 192.168.2.0/24 to another company located in that city. On the other hand, a large company may distribute its network addresses across geographical boundaries. For example, a large Internet service provider may be allocated 193.0.0.0/8. This Internet service provider may subdivide its network into smaller ranges for each geographical region in which it provides Internet access services. Thus, it may allocate 193.1.1.0/24 for a town and 193.2.0.0/16 for a large city.
If the network address of a user's computing device (e.g., client computing device) is known, various interesting applications become possible. For example, search results, advertising, weather reporting, and other applications can be highly tailored to the user's location.